The present invention relates generally to the printing art, and more particularly to a printing form and to a method and apparatus for making the same.
Printing forms of metal, for instance aluminum, which are embossed so as to have on one surface a plurality of spaced protuberances, are already known in the art. For instance, one such printing form is disclosed in U.S. Pat. No. 3,651,759 (Ritzerfeld) to which reference may be had for details.
Printing forms of this general type have heretofore had the depressions and corresponding protuberances cold-embossed by means of an embossing roller. When the form is to be used for printing purposes, that is when an image area is to be produced which can be printed, then writing was produced on it by means of a typewriter, a ballpoint pen or a scribing tool, or of course a drawing or the like was produced by means of a ballpoint pen or a scribing tool. In so doing, some of the protuberances were flattened out again to thus produce lines or areas which subsequently were to print a desired image corresponding to these lines or areas. A characteristic of these known printing forms provided with protuberances, is that the formation of pictures, drawings, writing or the like was produced purely mechanically by flattening out various of the protuberances. This has the disadvantage that it is impossible to produce the image areas on the printing form from a pattern sheet, for instance a transparent pattern sheet having image areas which could be correspondingly reproduced on the printing form. The image areas always had to be produced by means of a typewriter, scribing tool or the like, and for each printing form the operation of producing the image areas had to be repeated, even though the image areas to be produced on a plurality of printing forms might be identical.
A further disadvantage of the prior-art printing forms of the type here under discussion is the fact that any changes or corrections of the image areas were very difficult to carry out. If an error had been made, or if, after an image area was produced, it had been decided to make a correction, the only way this could be done would be to laboriously deform the material of the printing form again to in effect "erase" or eliminate the previously made deformation which had resulted in the formation of the image area, whereupon in the thus corrected portion of the printing form new protuberances had to be embossed, an operation which was then followed by re-creating the image area in the desired manner.
Still a further drawback of the prior-art printing forms of the type in question was the fact that the aluminum of which they were mostly made is relatively expensive. In some instances the aluminum was combined with layers or coatings of other material, and this has always heretofore made these printing forms relatively uneconomical to use.
Finally, these printing forms of the prior art have still an additional disadvantage, namely the fact that it is very difficult and expensive to provide them with form printing which in many instances is desired as a guide for the later user who is to produce the image area in the printing form, but which form printing must not be embossed into the printing form itself. Such form printing might, for instance, direct a user where to place a street address, a town of residence, telephone number or the like. To do this without at the same time deforming some of the protuberances was very difficult and expensive.